The invention relates to a novel smoker device for providing a layer of smoke reactant on a laboratory microscope slide.
The invention further relates to a device for safely burning a magnesium ribbon to provide a magnesium oxide layer on a microscope slide for measuring airborne droplets.
Under the prior art procedure, the magnesium oxide layers are formed on a microscope slide by moving a burning magnesium ribbon, held by forceps, back and forth under the slide at distance such that the tip of the flame just clears the glass when viewed through welder's goggles. The ends and edges of the smoke layer are then scraped to facilitate handling a detailed discussion of the preparation of magnesium oxide smoked slides and their use in detecting and measuring airborne droplets is disclosed in K. R. May, The Measurement of Airborne Droplets by the Magnesium Oxide Method, Journal Scientific Instrumentation, Vol. 27, pp. 128-130 (1950).
The prior art process of a magnesium oxide smoked slide suffered from a number of disadvantages. The burning magnesium ribbon had to be hand held and maneuvered under a glass slide, thus resulting in a hazardous burn problem to personnel and adjacent equipment due to the molten nature of the burning magnesium. The intense light given off by burning magnesium also presents a danger of serious eye damage. Though this problem can be minimized by wearing dark welder's goggles and closing of the area from unprotected personnel, the welder's goggles limit the visibility of the burner flame used to ignite the ribbon and thus create a serious burn hazard to the operator from the burner flame. Under the prior method, a uniform coating was difficult to obtain since two separate six inch pieces of magnesium ribbon had to be passed to and fro under the slide at a constant distance under the slide. As the ribbons burn, they must be raised to compensate for shortening due to burning. Any air current disturbances around the slides require an offsetting movement by the operator to compensate. The rejection rate for slides has thus run approximately 10% under a fume hood and 25% when the slides are prepared out of doors. Finally, the prior method required scraping of the slide to prevent the coating from flaking off the slide at the handling and labeling areas. Thus, an unsteady hand or unexpected shift of the slide under the pressure of scraping could result in ruined slides.
The smoker apparatus and method of this invention has overcome these prior art disadvantages in that there is no need for holding burning magnesium, wearing welding goggles or scraping and trimming of the coating on the slide. Microscope slides prepared by the instant smoker device have a uniform coating, regardless of the wind conditions under which the slide is prepared.